Transporting and towing vehicles such as damaged automobiles and the like, show cars, antique vehicles of various types and other similar transportation type of vehicles has become quite popular in recent years and the development of transport trucks to convey such vehicles has been undertaken.
Transport vehicles having rollback decks are well known as a means for transporting vehicles. U.S. Pat. No. 5,133,633, issued to "Grata" on Jul. 28, 1992, entitled "Low-Angle Slidably Supported Roll-Back Vehicle Transport Apparatus", which is incorporated herein by reference, illustrates one type of transport vehicle having a rollback deck. As detailed therein, such transport vehicles include a vehicle support surface or the rollback deck movably mounted on a truck bed frame. Specifically, the vehicle support surface is pivotable relative to the truck bed frame between a transport position and a loading position. In the transport position, the support surface is parallel to the bed frame. In the loading position, the support surface is at an angle relative to the bed frame such that it contacts the ground so as allow a disabled vehicle to be rolled thereon.
Another method of towing and transporting vehicles is the wheel-lift apparatus. Typical wheel-lift apparatuses carry disabled vehicles by lifting either the front or rear wheels off the ground, and towing the partially-lifted disabled vehicle on its remaining two wheels. U.S. patent application Ser. No. 08/555,211, filed on Nov. 8, 1995, now U.S. Pat. No. 5,713,714 entitled "Tilt Cylinder For an Underreach Assembly", which is incorporated herein by reference, illustrates one type of wheel-lift apparatus.
Other early versions of the lifting or towing vehicles have a wheel-lift apparatus in which the boom and related lifting mechanism are located beneath the deck of the lifting and towing vehicle; see U.S. Pat. No. 5,269,553, issued to "Alonso" on Dec. 14, 1993, entitled "Towing Apparatus and Thrust Reversal Mechanism Therefor". As shown in Alonso, the wheel-lift apparatus boom has an inner end pivotally mounted adjacent the rear axle and a wheel supporting cradle at an outer end. Similarly, U.S. Pat. No. 5,061,147, issued to "Nespor" on Oct. 29, 1993 (Reexamination Certificate No. B1 5,061,147, issued on Feb. 25, 1997), entitled "Vehicle Carrier with Wheel Lift", discloses a wheel-lift apparatus boom having an inner end pivotally mounted to struts and a bracket adjacent the rear axle and a wheel supporting cradle at an outer end. Each of the Alonso and Nespor booms are outwardly extended by hydraulic cylinders at an angle raised substantially from horizontal to the ground. Such devices suffer from a number of deficiencies, as explained below.
For example, referring to Alonso and Nespor, by utilizing a boom raised at a substantial slope to connect the wheel supporting cradle to the lifting or towing vehicle, there is a possibility of the supporting cradle or the boom hitting the disabled vehicle, often resulting in significant damage to the disabled vehicle. In some types of vehicles, such as vans and jeeps, the danger is minimal since there is a very short distance between the bumper and the adjacent wheel axle. However, on vehicles where there is substantial overhang of the body or chassis, beyond the rear and/or front axle the likelihood of damage to the disabled vehicle by the lifting wheel-lift apparatus is significant. A 1996 "CHEVROLET CAMARRO" is an example of a car which is likely to be damaged by many known wheel-lift apparatuses.
FIGS. 10 and 12 illustrate typical prior art wheel-lift apparatuses of a rollback transport vehicle. Referring to FIGS. 10 and 12, the conventional boom extends in the loading position with an angle substantially greater than horizontally parallel to the ground. The conventional boom hits the disabled vehicle because the slope and height of the boom is too great while it approaches the car in the loading position and/or lifts the car in the carrying position.
None of the patents described above provides the important advantages associated with towing vehicles comprising a boom capable of a substantial reach while maintaining a horizontally aligned or "low angle" approach and lift, between about -15 and 15 degrees during loading and carrying, respectively. In this manner an approach and lift is provided in which the boom operates horizontally to the ground.